<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="../css/reset.css">
    <style>
        .box {
            width: 300px;
            height: 300px;
            background-color: #f00;
            position: relative;
            margin: 300px;

            overflow: hidden;
        }

        .hide {
            width: 300px;
            height: 300px;
            background-color: #000;

            position: absolute;
            top: -300px;

            transition: 1s;
        }

        .box:hover .hide {
            top: 0;
        }
    </style>
</head>

<body>

    <div class="box">
        <div class="hide"></div>
    </div>

</body>

</html>